The Clay Minerals Society maintains a repository of Source Clays to provide scientists and researchers with a readily available supply of consistent materials so that research conducted by different groups can be correlated to identical material. These Source Clays include kaolinite, smectite, chlorite, vermiculite, illite, palygorskite and other minerals. As most of the Source Clays are naturally occurring materials, they typically contain minor to significant amounts of other mineral impurities. When conducting research using these samples, it is important that their mineral content be well characterized. It is also often desirable to remove these impurities to produce pure clay samples....